The present claimed invention relates to a light irradiating unit, a lighting unit and a method for manufacturing a lighting unit, more specifically to a light irradiating unit, a lighting unit and a method for manufacturing a lighting unit that is preferably used in a case of inspecting a product by making use of reflected illumination.
A light irradiating unit and a lighting unit on which a plurality of illuminants such as LEDs are arranged so as to irradiate light on an object portion to be irradiated with the illuminants surrounding the object portion so as to keep a luminous intensity of the object portion uniform has been developed.
In order to surround and cover the object portion to be irradiated, it is preferable to form an illuminant loading face in a shape of a curved concave face such as an inner face of a cylinder or a concave face of a cone frustum and a plurality of LEDs are loaded on all over the illuminant loading face. Conventionally in order to manufacture this kind of light irradiating unit, complicated manufacturing processes have been required such as a holding frame itself is formed to be an inner face of a cylinder or a concave face of a cone frustum and holes are bored on the holding frame, an illuminant is implanted into each hole and then a wiring is provided. Then the present claimed inventor has invented and patented a method for manufacturing this king of light irradiating unit in which a print substrate that can be curved are loaded with LEDs in a tabular state and then the print substrate is curved as shown in Japan Patent Laid Open No. 10-21729 in order to reduce a complicated process and a cost significantly.
However, it is extremely difficult for this kind of light irradiating unit and lighting unit to provide a heat dissipating structure in a back face of the curved illuminant loading face and actually almost no positive measure has been taken to dissipate heat. More concretely, as shown in FIG. 23, nothing is arranged in a back face of the LED 100 and there is airspace AS between the LED 100 and a holding frame. As a result of this, a temperature of the LED 100 cannot be lowered and there is much room for improvement such as a big light volume cannot be obtained, the luminous intensity is unstable and it is difficult to elongate life duration.
Further, with an arrangement in which the print substrate is curved and its flange is engaged with a holding frame the print substrate might be a little shaky or its curved face might become uneven.
In order to solve the above problems, the present claimed invention mainly intends to provide a light irradiating unit and the lighting unit in which a plurality of illuminants are arranged on a curved face that is easy to manufacture and that can get a big light volume, stable in the luminous intensity and superior in life duration.